Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
MORTIERELLAALPINA STRAIN AND USE THEREOF, MICROBIAL
OIL CONTAININGARAAT SN-2 POSITION
AND PREPARATION AND USES
THEREOF
TECHNICAL FIELD
The present disclosure relates to microbial technology, and more particularly
to
a Mortiereilaalpina strain and a use thereof, a microbial oil containing ARA
at an
Sn-2 position, and a preparation and uses thereof.
BACKGROUND
Lipids, as essential nutrients for human body, act as indispensable raw
materials
for building cells and tissues and supply energy for body, and they can also
act as a
carrier for the fat-soluble vitamins. However, before exerting their
biological and
physiological effects, lipids need to be digested and absorbed in the
intestines first.
Lipases from the pancreas and small intestines and cholate in the bile
participate in
the digestion and absorption of the lipids under an alkaline environment
formed by
bicarbonate secreted from the pancreas and bile. The lipid absorption
efficiency
greatly depends on the enzymes involved in the digestion and the action
mechanisms
thereof, and the structures of the lipid. A large number of studies have shown
that the
structures of the lipid largely influence the absorption rate of lipid in
human body.
With regard to the triglyceride, the fatty acids are classified into Sn-1, Sn-
2 and Sn-3
position fatty acids according to their positions on the glycerol skeleton.
Pancreatic
lipase, as a primary lipase enzyme, attaches to a water-oil interface to
hydrolyze
dietary fat molecules. Meanwhile, the pancreatic lipase specifically catalyzes
the
hydrolysis of ester bonds at the Sn-1 and Sn-3 positions. As a consequence,
under
the catalysis of the pancreatic lipase, the triglyceride structure is
converted into free
fatty acids and a monoglyceride. In the conversion, the free fatty acids are
from the
fatty acids at the Sn-1 and Sn-3 positions and, have difficulty in penetrating
into bile
salt micelle to be absorbed, such that they will combine with calcium and
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magnesium ions in the intestine to form insoluble soap salts to be wasted,
whereas
the monoglyceride formed from the fatty acid at the Sn-2 position is easy to
penetrate into bile salt micelle to be absorbed. Therefore, the absorption
rate of fatty
acids at the Sn-2 position in human body is higher than that of the fatty
acids at the
Sn-1 and Sn-3 positions.
As consumers become more aware of the health impact of fatty acids, microbial
oils, as primary resources of polyunsaturated fatty acids, have been largely
adopted
in the production of infant food and nutraceuticals, and their nutritional
benefits are
increasingly recognized by public. In addition, people are more and more
concerned
about the absorption rate of functional polyunsaturated fatty acids such as
arachidonic acid (ARA) and docosahexaenoic acid (DHA). 90% of fatty acids in
microbial oils exist in the form of triglyceride; however, in the existing
microbial
oils, the fatty acids at the Sn-2 position of triglyceride are far less than
those at the
Sn-1 and Sn-3 positions. Most of Sn-1 and Sn-3 fatty acids are formed into
soap salts
and wasted, which decreases the benefits of the microbial oils.
SUMMARY
The object of the present disclosure is to provide a Mortierellaalpina strain
and
a use thereof, a microbial oil containing arachidonic acid (ARA) at an Sn-2
position,
and a preparation and uses thereof, to solve the problem that in the existing
microbial
oils, ARA is mainly incorporated at Sn-1 and Sn-3 positions of triglyceride,
leading
to poor absorption rate of ARA in human body.
The microbial oil provided herein is produced by fermentation using
Mortierellaalpina, and Sn-2 fatty acids of the triglyceride in the microbial
oil
includes 23% or more by weight of the ARA, improving the absorption of ARA.
In order to realize the above-mentioned object, in a first aspect, the present
disclosure provides a microbial oil, comprising:
a triglyceride;
wherein Sn-2 fatty acids of the triglyceride comprise 23% or more by weight of
ARA.
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In some embodiments, a weight percentage of ARA in the microbial oil is not
less than 38%.
In a second aspect, the present disclosure further provides a method for
producing a microbial oil, comprising:
inoculating a Mortierellaalpina strain into a fermentation medium for
fermentation to produce the microbial oil;
wherein the Mortierellaalpina strain has an accession number of GDMCC No,
60734.
In a third aspect, the present disclosure provides a microbial oil produced by
the
above-mentioned method, wherein the microbial oil comprises a triglyceride;
and
Sn-2 fatty acids of the triglyceride comprise 23% or more by weight of ARA.
In a fourth aspect, the present disclosure provides a food comprising the
above-mentioned microbial oil, wherein the food is an infant formula food, a
nutraceutical or a health food.
In a fifth aspect, the present disclosure provides a Mortierellaalpina strain,
wherein the Mortierellaaipina strain has an accession number of GDMCC No.
60734.
In a sixth aspect, the present disclosure provides an application of the
above-mentioned Mortierellaalpina strain in the production of a microbial oil.
The microbial oil produced by the fermentation using Mortierellaalpina is rich
in ARA, and a weight percentage of the Sn-2 ARA of the triglyceride in the
microbial oil is not less than 23%, preferably 30%, which effectively
facilitates the
absorption and utilization ofARA in the microbial oil.
The features and beneficial effects will be further described in detail below
with
reference to the embodiments.
Deposit of microorganisms
The Mortierellaalpina strain of the present disclosure has been deposited in
Guangdong Microbial Culture Collection Center (GDMCC, Guangdong Institute of
Microbiology, 5th Floor, No. 59 Building, No. 100 Xianliezhong Road,
Guangzhou,
510070, China) on August 8, 2019 with an accession number of GDMCC No,
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60734.
DETAILED DESCRIPTION OF EMBODIMENTS
It should be noted that endpoints and values within ranges disclosed herein
are
only exemplary, and are intended to include any values close to these values
and
ranges. Any possible combination of numerical values within the range to form
one
or more new ranges should be considered to be expressly disclosed in this
disclosure.
In a first aspect, the present disclosure provides a microbial oil, where the
microbial oil includes a triglyceride, and Sn-2 fatty acids of the
triglyceride contain
23% or more by weight of ARA.
In some embodiments, the Sn-2 fatty acids of the triglyceride contain 30%,
preferably 31%, or more by weight of ARA.
The ARA is an abbreviation of arachidonic acid.
In some embodiments, the microbial oil includes 90% or more by weight of the
triglyceride.
In some embodiments, a weight percentage of ARA in the microbial oil is not
less than 38%.
It should be understood that the total ARA is a total amount of ARA in the
microbial oil, and is measured according the method of GB 26401-2011.
Triglyceride ARA refers to the ARA incorporated to the glycerol skeleton
through
ester bonds.
In some embodiments, a weight percentage of the Sn-2 ARA of the triglyceride
in the microbial oil is not less than 23%.
In some embodiments, a weight percentage of ARA at the Sn-2 position of the
triglyceride is not less than 23%, and a weight percentage of the triglyceride
ARA in
the microbial oil is not less than 38%.
In a second aspect, the present disclosure further provides a method for
producing a microbial oil, including:
inoculating a Mortierellaalpina strain into a fermentation medium for
fermentation to produce the microbial oil;
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where the Mortierellaalpina strain has an accession number of GDMCC No,
60734.
The strain can be obtained by a method conventionally used in the art.
The Niortierellaalpina GDMCC No. 60734 provided herein is obtained by
screening after mutagenesis.
The mutagenesis is performed according to a conventional method, such as
physical mutagenesis (ultraviolet mutagenesis, atmospheric room temperature
plasma (ARTP) mutagenesis) and chemical mutagenesis.
In some embodiments, the mutagenesis is performed by ARTP nnutagenesis.
The ARTP mutagenesis is carried out using a conventional mutagenesis system
such as multifunctional mutagenesis system (MPMS) produced by Adhoc Interteck
Co., Ltd. (Beijing, China).
The mutagenesis is performed according to conventional operations in the art.
In an embodiment, the mutagenesis is performed at a plasma mutagenesis power
of
80-120 W, a gas flow rate of 8-12 SLM (standard liter per minute) and a
treatment
distance of 1-3 mm.
The mutagenesis time is 1-6 min, preferably 180-210 s.
In some embodiments, a lethality of the Nlortierellaaipina strain is 90-95%
through the above-mentioned operations.
The mutagenesis can be performed on spores of a starting strain, and the
spores
can be provided in the form of a spore suspension. In some embodiments, the
spore
suspension is prepared through steps of: activating a starting strain on a
slant
medium to obtain the spores; and dispersing the spores in sterile water to
prepare the
spore suspension. Preferably, a concentration of the spore suspension is 106-
108
spores/mL.
After the strains obtained from the mutagenesis are subjected to multiple
screenings to obtain a strain with high yield of Sn-2 ARA.
It should be understood by those skilled in the art that the percentage of the
triglyceride with ARA at the Sn-2 position is used as an indicator for the
screening of
a desired high yield strain.
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The content of Sn-2 fatty acids is detected according to the method recited in
GB/T 24984-2010/IS0 6800:1997 "Animal and Vegetable Fats and
Oils¨Determination of the Composition of Fatty Acids in the 2-position of the
Triglyceride Molecules".
In order to obtain a strain with high stability, the strains obtained by
screening
can also be evaluated for genetic stability. It has been widely accepted in
the
verification of genetic stability in the modern breeding that if the strain
obtained
from the mutation breeding can still meet the expected requirements of
biological
characteristics after five passages, it is considered to have high stability.
Through the mutagenesis, screening and genetic stability evaluation mentioned
above, a strain with high yield of Sn-2 ARA is obtained.
The Mortierellaalpina strain of the present disclosure has been deposited in
Guangdong Microbial Culture Collection Center (GDMCC, Guangdong Institute of
Microbiology, 5t Floor, No. 59 Building, No. 100 Xianliezhong Road, Guangzhou,
510070, China) on August 8, 2019 with an accession number of GDMCC No,
60734.
An Sn-2 ARA-rich microbial oil is produced by the fermentation using the
Mortierellaalpina strain, and the fermentation method has no special
requirements as
long as it enables the proliferation of the Mortierellaalpina strain.
There are no special requirements for the fermentation by the
Mortierellaalpina
strain. In some embodiments, the fermentation is performed at 27-31 C for 4-8
days
under a ventilation rate of 0.5-1.1 vvm.
When the Mortierellaalpina strain is inoculated in the form of a seed liquid,
the
inoculation amount can be selected in a wide range, such as 5-10% (vIv).
The fermentation medium used herein can be a medium commonly used in the
art for the fermentation by the Mortierellaalpina. The fermentation medium
includes
a carbon source and a nitrogen source.
The carbon source is glucose, sucrose, starch or other substances that can
provide a carbon source or a combination thereof, and the nitrogen source is
peptone,
yeast powder, corn steep liquor powder or other substances that can provide a
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nitrogen source or a combination thereof.
Preferably, the carbon source is selected from the group consisting of
glucose,
starch, sucrose and a combination thereof, and the nitrogen source is selected
from
the group consisting of peptone, yeast powder, yeast extract, corn steep
liquor
powder and a combination thereof.
The carbon-to-nitrogen ratio can be selected in a wide range. Preferably, the
carbon-to-nitrogen ratio is (3-18):1.
During the fermentation, the nitrogen source is added into the fermentation
medium at one time, and beside the initial addition, the carbon source can be
continuously supplied to adjust the carbon-to-nitrogen ratio. When approaching
the
fermentation end, the carbon source is not supplied into the medium any more
so
that the residual sugar is reduced to 0. In this way, an auxotrophic condition
is
created by adjusting the carbon-to-nitrogen ratio to improve the oil
production of the
Mortierellaalpina strain,
In order to increase a yield of the fermentation product, in some embodiments,
the method further includes: activating the Mortierellaalpina strain followed
by
expansion culture to obtain a seed liquid; and then inoculating the seed
liquid into
the fermentation medium for fermentation.
The seed liquid is prepared according to a method conventionally used in the
art.
Preferably, the seed liquid is prepared through steps of
(1) activating the Mortierellaalpina strain to obtain a spore suspension;
(2) inoculating the spore suspension into a seed culture medium followed by
shake flask expansion culture to obtain a primary seed liquid; and
(3) inoculating the primary seed liquid obtained in step (2) into an expansion
culture medium followed by seed tank expansion culture to obtain the target
seed
liquid.
The spore suspension provided herein can be prepared by one or more
activations.
The activation is performed at 25-30 C for 4-7 days.
Preferably, in step (1), the activating process includes the following steps:
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inoculating the Mortierellaalpina strain into a primary activation medium
followed by culture at 25-30 C for 5-7 days to obtain primary activated
spores; and
inoculating the primary activated spores into a secondary activation medium
followed by culture at 25-30 C for 4-6 days to obtain mature spores and
hyphae, and
preparing a spore suspension.
The primary activation medium and the secondary activation medium used
herein are the medium conventionally used in the art to activate the
Mortierellaalpine strain. Preferably, the primary activation medium and the
secondary activation medium are independently a potato dextrose agar (PDA)
solid
medium.
The PDA medium used herein is purchased or self-made. Preferably, the PDA
medium contains 100-300 g/L of potato and 10-30 g/L of sucrose. For the solid
PDA
medium, 15-17 g/L of agar is additionally added.
The Mortierellaalpina strains are preserved in an ampoule or a glycerin tube.
In some embodiments, the primary activation is performed on a slant medium in
a test tube.
In some embodiments, the secondary activation is performed on a slant medium
in an eggplant-shaped flask.
In some embodiments, the mature spores and hyphae are washed with water to
prepare the spore suspension. Preferably, the water is sterile water.
Preferably, in step (2), the shake flask expansion culture is performed at
25-30 C for 5-8 days.
Preferably, the seed culture medium includes a carbon source and a nitrogen
source. A concentration of the carbon source is 50-70 g/L; a concentration of
the
nitrogen source is 15-25 g/L; and a pH value of the seed culture medium is 6.5-
7.2.
The shake flask expansion culture is performed at 180 r/min on a shaker.
Preferably, in step (3), the primary seed liquid obtained in step (2) is
inoculated
into the expansion culture medium and then undergoes a seed tank expansion
culture
to obtain the target seed liquid.
Preferably, the seed tank expansion culture is performed at 27-31 C for 1-2
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days under a ventilation rate of 0.5-0.8 vvm.
Preferably, the expansion culture medium includes a carbon source and a
nitrogen source, and a carbon-to-nitrogen ratio is (3-8):1.
In some embodiments, in step (3), the primary seed liquid obtained in step (2)
is
inoculated into a primary expansion culture medium for primary expansion
culture,
and then inoculated into a secondary expansion culture medium for secondary
expansion culture to obtain the target seed liquid.
Preferably, the primary expansion culture is performed at 27-31 C for 1-2 days
under a ventilation rate of 0.5-0.8 vvm.
Preferably, the secondary expansion culture is performed at 27-31 C for 1-2
days under a ventilation rate of 0.5-0.8 vvm.
Preferably, the primary expansion culture medium includes a carbon source and
a nitrogen source, and a carbon-to-nitrogen ratio is (3-8):1.
Preferably, the secondary expansion culture medium includes a carbon source
and a nitrogen source, and a carbon-to-nitrogen ratio is (3-8):1.
The types of carbon sources and nitrogen sources in the various medium used
herein refer to the carbon sources and nitrogen sources described in the
fermentation
medium.
In some embodiments, the target seed liquid is prepared according to the
following steps:
(1) inoculating the Mortiereliaalpina strain into a PDA slant medium followed
by culture until spores appear and mature; and preparing a spore suspension;
(2) inoculating the spore suspension obtained in step (1) into a seed culture
medium in a shake flask; and
(3) inoculating the culture in the shake flask into a primary seed tank
followed
by culture for 1-2 days; and inoculating the culture in the primary seed tank
into a
secondary seed tank followed by culture for 1-2 days to obtain the target seed
liquid.
Preferably, in the step (1), the Mortierellaalpina strain is inoculated onto
the
PDA slant medium in a test tube, and cultured at 25-30 C for 5-7 days for the
growth
of the spores.; then the spores are inoculated into a PDA slant medium in an
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eggplant-shaped flask, and cultured at 25-30 C for 4-6 days to allow the
spores to
mature. Hyphae and the spores on the PDA slant medium are collected and
prepared
into the spore suspension with sterile water.
Preferably, in the step (2), the spore suspension obtained in step (1) is
inoculated into the seed culture medium in the shake flask, and cultured at 25-
30 C
and 180-200 r/min for 3-6 days, where the seed culture medium contains 50-70
g/L
of the carbon source and 15-25 g/L of the nitrogen source, and has a pH of 6.8-
7.2.
Specifically, the spores in each eggplant-shaped flask are inoculated into 2-3
shake
flasks, and volumes of the eggplant-shaped flask and the shake flask are both
500
ML.
Specifically, in the step (3), the culture in the primary seed tank is
performed at
27-31 C for 1-2 days, where a ventilation rate is 0.5-0.8 vvm and a
carbon-to-nitrogen ratio is (3-8):1, and then the culture in the secondary
seed tank is
performed at 27-31 C for 1-2 days, where a ventilation rate is 0.5-0.8 vvm and
a
carbon-to-nitrogen ratio is (3-8):1.
The present disclosure may further process the above-mentioned fermentation
product to obtain a microbial oil. There are no special requirements for the
processing method as long as the method can extract the microbial oil from the
fermentation product. In order to improve the production of the microbial oil,
the
fermentation product is subjected to extraction.
In a third aspect, the present disclosure provides a microbial oil produced by
the
method mentioned above. The microbial oil includes a triglyceride, and Sn-2
fatty
acids of the triglyceride include 23% or more by weight of ARA.
Preferably, a weight percentage of ARA in the microbial oil is not less than
38%.
In a fourth aspect, the present disclosure further provides a food including
the
microbial oil mentioned above.
Preferably, the food is an infant formula food, a nutraceutical or a health
food.
In a fifth aspect, the present disclosure provides a Mortierellaalpina strain,
where the Mortierellaalpina strain has an accession number of GDMCC No. 60734.
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The method for obtaining the Mortierellaalpina strain has been described in
the
second aspect, and will not be repeated here.
In a sixth aspect, the present disclosure provides a use of the
Mortierellaalpina
strain in the production of the microbial oil.
Preferably, the microbial oil includes a triglyceride, and Sn-2 fatty acids of
the
triglyceride include 23% or more by weight of ARA.
Preferably, a weight percentage of ARA in the microbial oil is not less than
38%.
The present disclosure will be further described in detail below with
reference
to the embodiments.
In the embodiments, a content of ARA in a microbial oil is detected according
to GB 26401-2011; and a fatty acid composition of the microbial oil is
detected
according to GB 5009. 168-2016.
The absorption rate of ARA in human body is evaluated by an efficacy trial,
where male and female subjects are required to take in the microbial oil
produced by
the method of the present disclosure and a control microbial oil produced by
an
ordinary Mortierellaalpina strain, and then blood samples are collected to
determine
a content of the Sn-2 ARA in the blood to calculate the absorption rate of
ARA.
The ordinary Mortierella alpina strain is provided by China Center of
Industrial
Culture Collection, and has an accession number of CICC 11092s.
The glucose, starch, yeast powder, yeast extract, peptone, a corn steep liquor
powder, potatoes and agar are all commercially available.
The PDA culture medium used herein contains 200 g of potatoes, 20 g of
sucrose, 15-17 g of agar and 1000 mL of water.
The method provided herein for producing microbial oil by fermentation using
Mortierellaalpine will be specifically described in Examples 1-3.
Preparation Example
Preparation of Mortierellaalpina strain (GDM CC No.60734)
A parent strain preserved in the ampoule inoculated onto a PDA slant medium
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and cultured at 27 C for 5 days. The grown spores were transferred to another
PDA
slant medium and cultured at 27 C for 4 days to be mature. The mature spores
were
washed off with 20 mL of sterile water to prepare a spore suspension, and a
concentration of the spore suspension was adjusted to 106-108 spores/mL.
1 p.1_, of the spore suspension was spread to a sterilized sample slide, and
was
subjected to ARTP mutagenesis in a multifunctional mutagenesis system (MPMS)
produced by Adhoc lnterteck Co., Ltd. (Beijing, China), where the ARTP
mutagenesis was carried out at a plasma mutagenesis power of 100 W, a gas flow
rate of 10 SLM and a treatment distance of 2 mm for 25 s, and a lethality rate
was
93.33%. Well-grown single colonies were selected for passage, and then
inoculated
into a shake flask containing the PDA medium and cultured at 27 C for 4 days.
A
preliminary screening was performed to detect a content of the Sn-2 position
ARA in
the culture to select high-yield strains. The high-yield strains obtained by
the
preliminary screening were subjected to secondary screening by culture in a
shake
flask at 27 C for 4 days to further select high-yield strains. The genetic
stability of
the high-yield strains obtained by the secondary screening was investigated.
After 5
passages, the strain with stable genetic traits was used as the production
strain and
stored for long-term use.
After screening, the Mortierellaalpina strain GDMCC No. 60734 of the present
disclosure was obtained, which had been deposited in Guangdong Microbial
Culture
Collection Center (GDMCC, Guangdong Institute of Microbiology, 5th Floor, No.
59
Building, No. 100 Xianliezhong Road, Guangzhou, 510070, China) on August 8,
2019.
Example 1
Preparation of a microbial oil by fermentation using the Mortierellaalpine
strain
GDMCC No. 60734
(1) An ordinary Mortierellaalpine strain and the Ivlortierellaalpine strain
GDMCC No. 60734 used herein were inoculated onto a PDA slant medium in a test
tube, respectively, and cultured at 27 C for 5 days. The grown spores were
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inoculated into a PDA slant medium in an eggplant-shaped flask, and cultured
at
27 C for 4 days to become mature. The hyphae and the spores on the medium were
washed off with 20 mL of sterile water to prepare a spore suspension.
(2) The spore suspension obtained in step (1) was inoculated into a seed
culture
medium in a shake flask, and cultured at 27 C and 180 r/min on a shaker for 4
days,
where the spore suspension in each eggplant-shaped flask was inoculated into 2-
3
shake flasks, and the seed culture medium contained 50 g/L of glucose and 15
g/L of
yeast powder, and had a pH of 7.2.
(3) 1 L of the culture in the shake flasks was inoculated in a 1 m3 primary
seed
tank containing 500 L of a primary expansion culture medium, and cultured at
29 C
and 180 r/nnin under a ventilation rate of 0.65 vvm for 2 days, where the
primary
expansion culture medium contained 30 g/L of glucose and 15 g/L of yeast
extract,
and had a pH of 7.2.
(4) 500 L of the culture product in the primary seed tank obtained in step (3)
was inoculated in a 10 rn3 secondary seed tank containing 7 nn3 of a secondary
expansion culture medium, and cultured at 29 C and 120 r/nnin under a
ventilation
rate of 0.65 vvm for 2 days, where the secondary expansion culture medium
contained 30 g/L of glucose and 15 g/L of yeast extract, and had a pH of 7.2.
A seed
liquid was obtained when a concentration of the hyphae reached 3.5%, and then
transferred to a fermentation tank.
(5) 2 m3 of the seed liquid obtained in step (4) was inoculated into a 45 m3
fermentation tank containing 22 m3 of a fermentation medium, and cultured at
29 C
and 90 r/min under a ventilation rate of 0.9 vvm for 6 days to obtain a
fermentation
product, where the carbon-nitrogen ratio was controlled at (8-16):1 by adding
a
sterile glucose solution (250 g/L) during the fermentation, and the
fermentation
medium contained 30 g/L of sucrose and 15 g/L of yeast extract, and had a pH
of
7.5.
(6) The fermentation product obtained in step (5) was separated to obtain wet
cells, which were dried and subjected to extraction with hexane to obtain an
oil. The
solid phase separated after extraction was transferred to an extraction vessel
for
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repeated extraction 4-7 times, and the oil remaining in the residue after
extractions
was controlled to be less than 7%. A weight ratio of the solvent to the dried
cell
during the extraction was 1.5:1. The oil phases obtained by filtration and
separation
after each extraction were combined and desolventized to obtain a microbial
oil.
(7) The microbial oil obtained in step (6) was detected to obtain a content of
ARA, a fatty acid composition and a weight percentage of ARA at the Sn-2
position
of triglyceride in the microbial oil, and the results were shown in Table 1.
Table 1 Parameters of the microbial oils in Example 1
Ordinary Mortierellaalpina
Mortiereliaalpina
strain
GDMCC No. 60734
ARA (C20:4), g/100g 40.71 44.067
Palmitic acid (C16:0), g/100g 7.356 7.274
Stearic acid (C18:0), g/100g 6.825 6.714
Oleic acid (C18:1), g/100g 6.013 5.924
Linoleic acid (C18:2), g/100g 5.922 6.044
Weight percentage of ARA at the Sn-2
21.97 32.65
position of triglyceride, %
Weight percentage of A RA at Sn-1 and
56.15 52.8
Sn-3 positions of triglyceride, %
Absorption rate ofARA, % 46.7 65.7
Example 2
Preparation of a microbial oil by fermentation using the Mortierellaalpine
strain
GDMCC No. 60734
(1) An ordinary Mortierellaalpine strain and the fvfortierellaalpine strain
GDMCC No. 60734 used herein were inoculated onto a PDA slant medium in a test
tube, respectively, and cultured at 28 C for 6 days. The grown spores were
inoculated into a PDA slant medium in an eggplant-shaped flask, and cultured
at
28 C for 5 days to become mature. The hyphae and the spores on the medium were
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washed off with 20 mL of sterile water to prepare a spore suspension.
(2) The spore suspension obtained in step (1) was inoculated into a seed
culture
medium in a shake flask, and cultured at 28 C and 200 r/min on a shaker for 5
days,
where the spore suspension in each eggplant-shaped flask was inoculated into 2-
3
shake flasks, and the seed culture medium contained 60 g/L of glucose, 10 g/L
of
yeast powder and 10 g/L of peptone, and had a pH of 7Ø
(3) 200 mL of the culture in the shake flasks was inoculated into a 5 L seed
tank
containing 3 L of an expansion culture medium, and cultured at 28 C and 200
r/min
under a ventilation rate of 0.6 vvnn for 1 day to obtain a seed liquid, where
the
expansion culture medium contained 35 WI_ of glucose and 20 g/L of yeast
powder,
and had a pH of 7.2.
(4) 1.5 L of the seed liquid obtained in step (3) was inoculated into a 30 L
fermentation tank containing 15 L of a fermentation medium, and cultured at 28
C
and 220 r/min under a ventilation rate of 0.8 vvm for 7 days to obtain a
fermentation
product, where the carbon-nitrogen ratio was controlled at (5-12):1 by adding
a
sterile glucose solution (250 g/L) during the fermentation, and the
fermentation
medium contained 50 g/L of glucose, 10 g/L of starch and 20 g/L of yeast
extract,
and had a pH of 8.
(5) The fermentation product obtained in step (4) was separated to obtain wet
cells, which were dried and subjected to extraction with hexane to obtain an
oil. The
solid phase separated after extraction was transferred to an extraction vessel
for
repeated extraction 4-7 times, and the oil remaining in the residue after
extractions
was controlled to be less than 7%. A weight ratio of the solvent to the dried
cell
during the extraction was 1.5:1. The oil phases obtained by filtration and
separation
after each extraction were combined and desolventized to obtain a microbial
oil.
(6) The microbial oil obtained in step (5) was detected to obtain a content of
ARA, a fatty acid composition and a weight percentage of ARA at the Sn-2
position
of triglyceride in the microbial oil, and the results were shown in Table 2.
Table 2 Parameters of the microbial oils in Example 2
CA 03149978 2022-3-2
Ordinary Mortierellaalpina
Mortiereliaalpina
strain
GDMCC No. 60734
ARA (C20:4), 9/1009 39.36 43.18
Palmitic acid (C16:0), g/100g 8.541 7.236
Stearic acid (C18:0), g/100g 7.136 6.696
Oleic acid (C18:1), g/100g 6.132 5.891
Linoleic acid (C18:2), g/100g 5.879 6.007
Weight percentage ofARA at Sn-2
20.97 32.17
position of triglyceride, %
Weight percentage of A RA at Sn-1 and
57.83 51.4
Sn-3 positions of triglyceride, %
Absorption rate ofARA, % 43.8 62.1
Example 3
Preparation of a microbial oil by fermentation using the Mortierellaalpine
strain
GDMCC No. 60734
(1) An ordinary Mortierellaalpine strain and the Mortierellaalpine strain
GDMCC No. 60734 used herein were inoculated onto a PDA slant medium in a test
tube, respectively, and cultured at 29 C for 7 days. The grown spores were
inoculated into a PDA slant medium in an eggplant-shaped flask, and cultured
at
29 C for 6 days to become mature. The hyphae and the spores on the medium were
washed off with 20 mL of sterile water to prepare a spore suspension.
(2) The spore suspension obtained in step (1) was inoculated into a seed
culture
medium in a shake flask, and cultured at 29 C and 190 r/min on a shaker for 6
days,
where the spore suspension in each eggplant-shaped flask was inoculated into 2-
3
shake flasks, and the seed culture medium contained 60 g/L of glucose, 25 g/L
of
yeast powder and 10 g/L of starch, and had a pH of 7.2.
(3) 300 mL of the culture in the shake flasks was inoculated into a 10 L seed
tank containing 6 L of an expansion culture medium, and cultured at 30 C and
220
r/min under a ventilation rate of 0.75 vvnn for 2 days to obtain a seed
liquid, where
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the expansion culture medium contained 40 WI_ of glucose and 25 g/L of yeast
powder, and had a pH of 6.8.
(4) 2.75 L of the seed liquid obtained in step (3) was inoculated into a 100 L
fermentation tank containing 55 L of a fermentation medium, and cultured at 30
C
and 200 r/min under a ventilation rate of 0.85 vvm for 5 days to obtain a
fermentation product, where the carbon-nitrogen ratio was controlled at (3-
10):1 by
adding a sterile glucose solution (250 g/L) during the fermentation, and the
fermentation medium contained 45 g/L of glucose, 10 g/L of corn steep liquor
powder and 10 g/L of peptone, and had a pH of 7Ø
(5) The fermentation product obtained in step (4) was separated to obtain wet
cells, which were dried and subjected to extraction with hexane to obtain an
oil. The
solid phase separated after extraction was transferred to an extraction vessel
for
repeated extraction 4-7 times, and the oil remaining in the residue after
extractions
was controlled to be less than 7%. A weight ratio of the solvent to the dried
cell
during the extraction was 1.5:1. The oil phases obtained by filtration and
separation
after each extraction were combined and desolventized to obtain a microbial
oil.
(6) The microbial oil obtained in step (5) was detected to obtain a content of
ARA, a fatty acid composition and a weight percentage of ARA at the Sn-2
position
of triglyceride in the microbial oil, and the results were shown in Table 3.
Table 3 Parameters of the microbial oils in Example 3
Ordinary Mortierellaalpina
Mortiereliaalpina
strain
GDMCC No. 60734
ARA (C20:4), g/100g 38.73 41.17
Palmitic acid (C16:0), 9/1009 8.136 7.257
Stearic acid (C18:0), g/100g 7.167 6.721
Oleic acid (C18:1), g/100g 6.939 5.916
Linoleic acid (C18:2), g/100g 6.871 6.009
Weight percentage ofARA at Sn-2
20.15 31.98
position of triglyceride, %
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Weight percentage of A RA at Sn-1 and
56.91 52.31
Sn-3 positions of triglyceride, %
Absorption rate ofARA, % 42.1 63.1
The above-mentioned embodiments are only preferred embodiments of the
disclosure, and are not intended to limit the scope of the present disclosure.
It should
be noted that variations and modifications made by those of ordinary skill in
the art
without departing from the spirit of the disclosure should fall within the
scope of the
present disclosure.
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